The present invention relates to a new and distinctive pepper (Capsicum annuum) inbred line designated PPL0789. All publications cited in this application are herein incorporated by reference.
There are numerous steps in the development of any new and novel desirable plant germplasm. Plant breeding begins with the analysis and definition of problems and weaknesses of the current germplasm, the establishment of program goals, and the definition of specific breeding objectives. The next step is selection of germplasm that possess the traits to meet the program goals and the best breeding method to reach those goals. The objective is to combine in a single inbred or hybrid an improved combination of desirable traits from the parental germplasm. These important characteristics may include higher yield, improved field performance, fruit and agronomic quality such as fruit shape and size, resistance to diseases and insects, and tolerance to drought and heat.
The bell pepper (Capsicum annuum) originated in Mexico and the neighboring areas of Central America. Soon after Columbus' discovery of this plant, it was grown worldwide and used as a spice and a medicine. Today, pepper plants can be found growing wild in tropical areas around the world. Many countries grow it as a crop. Many of the hot peppers can be found in Latin America and China, but the US prefers sweet bell peppers. Peppers are used for fresh consumption, and they are processed into powders, sauces, and salsas. Many of the new cultivars grown today can be traced back to the early plants.
Mild, sweet bell peppers have established themselves as staples in salads and as integral components of almost all sectors of American national and regional cuisine. However, American affection for peppers (Capsicum annuum) is not just limited to the established mild peppers. The American “hot food craze” is creating increasing demand and local markets for pungent chili pepper condiment products, locally grown fresh peppers and pepper-related products or productions such as festivals, clothing, artwork and publications. In the last few years, U.S. consumption of peppers has increased, moving from an average of 12 pounds per person in 2001 to 13 pounds in 2007. During that same time, consumption of bell peppers retreated to 6.8 pounds, matching the consumption rate in 2001.
California leads the nation in bell pepper production (7.0 million cwt worth $179 million), followed by Florida (4.3 million cwt worth $183.2 million) and Georgia (1.2 million cwt worth $40.2 million). In 2007, 14.7 million cwt of bell peppers were grown, valued at nearly $468.4 million. New Mexico still leads the nation in chili pepper production (1.9 million cwt worth $32.9 million), followed by California (1.8 million cwt worth $61.9 million). In 2007, 4.2 million cwt of chili peppers were grown, valued at nearly $120 million. According to the USDA, the United States ranked fifth in pepper production in 2007, growing nearly 19 million cwt. With a pepper production of 287 million cwt, China was, by far, the largest producer, followed by Turkey (41 million cwt) and Mexico (37 million cwt). (Huntrods, D., AgMRC, Bell and Chili Peppers Profile, Iowa State University, Rev. November 2008).
Bell peppers are eaten raw, cooked, immature and mature. Often nutritional content is altered by the changes in the way they are consumed. Per capita consumption of bell peppers in 1995 was 6.2 pounds. They are an excellent source of Vitamin C, Vitamin A, and calcium. Red peppers have more of these qualities than the immature green peppers.
Peppers grown in temperate regions are herbaceous annuals, but are herbaceous perennials where temperatures do not drop below freezing. Pepper plants' growth habit may be prostrate, compact, or erect, but it is determinate in that after it produces nine to eleven leaves a single stem terminates in flowers. These plants are grown for the edible fleshy fruit produced by this dichotomous growth. Peppers are non-climacteric which means they do not produce ethylene. They need to stay on the vine to continue the ripening process. A deep taproot will form if the plant root system is uninjured during transplanting. The spindle root will develop fibrous secondary root systems spreading laterally and downward. On the soil surface the stem will produce adventitious roots, but not as easily as the stem of a tomato. The leaves of the pepper plant arise singly and are simple, entire, and asymmetrical. Typical of all Solanaceous plants, the leaves are arranged alternately on the stem. They are shiny and glabrous and vary in shape from broadly ovate to ovate lanceolate. The flowers develop singly or in twos or threes continuously as the upper structure of the plant proliferates. The corolla is white and five lobed while the anthers are bluish or yellowish in color. The flowers have an open anther formation and will indefinitely self-pollinate. They are also pollinated by insects, which increases the chances of cross-pollination. Unlike tomatoes, whose pollen becomes nonviable in high temperatures, the pepper flowers' pollen is not extremely heat sensitive and it remains viable up to 100° Fahrenheit producing fruit throughout the season.
The fruit of a pepper plant is classified as a berry with colors from green, yellow, red, purple, black, brown, white and orange. Green is an immature fruit, yet commonly eaten this way, and as the fruit matures it changes color. In most commercial cultivars color changes are from green to red, green to yellow or green to orange. Usually, fruits of the purple and white varieties have these colors as they develop, and therefore do not have a green stage. For fruit to set, the ovaries need to be fertilized. Auxin is then produced by the seeds, which determine fruit cell elongation. The number of seeds fertilized will determine the size and shape of the fruit. The seed develop on the interior and attach to the veins. A fully developed seed is kidney shaped. There are about 4,500 seeds per ounce.
The method chosen for breeding or selection depends on the mode of plant reproduction, the heritability of the trait(s) being improved, and the type of cultivar used commercially (e.g., F1 hybrid cultivar, pureline cultivar, etc.). For highly heritable traits, a choice of superior individual plants evaluated at a single location will be effective, whereas for traits with low heritability, selection should be based on mean values obtained from replicated evaluations of families of related plants. Popular selection methods commonly include pedigree selection, modified pedigree selection, mass selection, and recurrent selection.
The complexity of inheritance influences choice of breeding method. Backcross breeding is used to transfer one or a few favorable genes for a highly heritable trait into a desirable cultivar. This approach has been used extensively for breeding disease-resistant cultivars. Various recurrent selection techniques are used to improve quantitatively inherited traits controlled by numerous genes. The use of recurrent selection in self-pollinating crops depends on the ease of pollination, the frequency of successful hybrids from each pollination, and the number of hybrid offspring from each successful cross.
Each breeding program should include a periodic, objective evaluation of the efficiency of the breeding procedure. Evaluation criteria vary depending on the goal and objectives, but should include gain from selection per year based on comparisons to an appropriate standard, overall value of the advanced breeding lines, and number of successful cultivars produced per unit of input (e.g., per year, per dollar expended, etc.).
Promising advanced breeding lines are thoroughly tested and compared to appropriate standards in environments representative of the commercial target area(s) for three years at least. The best lines are candidates for new commercial cultivars; those still deficient in a few traits are used as parents to produce new populations for further selection.
These processes, which lead to the final step of marketing and distribution, usually take from five to ten years from the time the first cross or selection is made. Therefore, development of new cultivars is a time-consuming process that requires precise forward planning, efficient use of resources, and a minimum of changes in direction.
A most difficult task is the identification of individuals that are genetically superior, because for most traits the true genotypic value is masked by other confounding plant traits or environmental factors. One method of identifying a superior plant is to observe its performance relative to other experimental plants and to a widely grown standard cultivar. If a single observation is inconclusive, replicated observations provide a better estimate of its genetic worth.
The goal of pepper plant breeding is to develop new, unique and superior pepper cultivars. The breeder initially selects and crosses two or more parental lines, followed by repeated selfing and selection, producing many new genetic combinations. The breeder can theoretically generate billions of different genetic combinations via crossing, selfing and mutations. The breeder has no direct control at the cellular level. Therefore, two breeders will never develop the same line having the same pepper traits.
Each year, the plant breeder selects the germplasm to advance to the next generation. This germplasm is grown under different geographical, climatic and soil conditions, and further selections are then made, during and at the end of the growing season. The cultivars that are developed are unpredictable. This unpredictability is because the breeder's selection occurs in unique environments, with no control at the DNA level (using conventional breeding procedures), and with millions of different possible genetic combinations being generated. A breeder of ordinary skill in the art cannot predict the final resulting lines he develops, except possibly in a very gross and general fashion. The same breeder cannot produce the same line twice by using the exact same original parents and the same selection techniques. This unpredictability results in the expenditure of large research monies to develop superior pepper cultivars.
The development of commercial pepper cultivars requires the development of pepper parental lines, the crossing of these lines, and the evaluation of the crosses. Pedigree breeding and recurrent selection breeding methods are used to develop cultivars from breeding populations. Breeding programs combine desirable traits from two or more varieties or various broad-based sources into breeding pools from which lines are developed by selfing and selection of desired phenotypes. The new lines are crossed with other lines and the hybrids from these crosses are evaluated to determine which have commercial potential.
Pedigree breeding is used commonly for the improvement of self-pollinating crops or inbred lines of cross-pollinating crops. Two parents which possess favorable, complementary traits are crossed to produce an F1. An F2 population is produced by selling one or several F1s or by intercrossing two F1s (sib mating). Selection of the best individuals is usually begun in the F2 population; then, beginning in the F3, the best individuals in the best families are selected. Replicated testing of families, or hybrid combinations involving individuals of these families, often follows in the F4 generation to improve the effectiveness of selection for traits with low heritability. At an advanced stage of inbreeding (i.e., F6 and F7), the best lines or mixtures of phenotypically similar lines are tested for potential release as new cultivars.
Mass and recurrent selections can be used to improve populations of either self- or cross-pollinating crops. A genetically variable population of heterozygous individuals is either identified or created by intercrossing several different parents. The best plants are selected based on individual superiority, outstanding progeny, or excellent combining ability. The selected plants are intercrossed to produce a new population in which further cycles of selection are continued.
Backcross breeding has been used to transfer genes for a simply inherited, highly heritable trait into a desirable homozygous cultivar or line that is the recurrent parent. The source of the trait to be transferred is called the donor parent. The resulting plant is expected to have the attributes of the recurrent parent (e.g., cultivar) and the desirable trait transferred from the donor parent. After the initial cross, individuals possessing the phenotype of the donor parent are selected and repeatedly crossed (backcrossed) to the recurrent parent. The resulting plant is expected to have the attributes of the recurrent parent (e.g., cultivar) and the desirable trait transferred from the donor parent.
The single-seed descent procedure in the strict sense refers to planting a segregating population, harvesting a sample of one seed per plant, and using the one-seed sample to plant the next generation. When the population has been advanced from the F2 to the desired level of inbreeding, the plants from which lines are derived will each trace to different F2 individuals. The number of plants in a population declines each generation due to failure of some seeds to germinate or some plants to produce at least one seed. As a result, not all of the F2 plants originally sampled in the population will be represented by a progeny when generation advance is completed.
In addition to phenotypic observations, the genotype of a plant can also be examined. There are many laboratory-based techniques available for the analysis, comparison and characterization of plant genotype; among these are Isozyme Electrophoresis, Restriction Fragment Length Polymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs), Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA Amplification Fingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs), Amplified Fragment Length polymorphisms (AFLPs), Simple Sequence Repeats (SSRs—which are also referred to as Microsatellites), and Single Nucleotide Polymorphisms (SNPs).
Isozyme Electrophoresis and RFLPs have been widely used to determine genetic composition. Shoemaker and Olsen, (Molecular Linkage Map of Soybean (Glycine max) pp. 6.131-6.138 in S. J. O'Brien (ed) Genetic Maps: Locus Maps of Complex Genomes, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., (1993)) developed a molecular genetic linkage map that consisted of 25 linkage groups with about 365 RFLP, 11 RAPD, three classical markers and four isozyme loci. See also, Shoemaker, R. C., RFLP Map of Soybean, p 299-309, in Phillips, R. L. and Vasil, I. K., eds. DNA-Based Markers in Plants, Kluwer Academic Press, Dordrecht, the Netherlands (1994).
SSR technology is currently the most efficient and practical marker technology; more marker loci can be routinely used and more alleles per marker locus can be found using SSRs in comparison to RFLPs. For example, Diwan and Cregan described a highly polymorphic microsatellite locus in soybean with as many as 26 alleles. (Diwan, N. and Cregan, P. B., Theor. Appl. Genet., 95:22-225, 1997.) SNPs may also be used to identify the unique genetic composition of the invention and progeny varieties retaining that unique genetic composition. Various molecular marker techniques may be used in combination to enhance overall resolution.
Molecular markers, which include markers identified through the use of techniques such as Isozyme Electrophoresis, RFLPs, RAPDs, AP-PCR, DAF, SCARs, AFLPs, SSRs, and SNPs, may be used in plant breeding. One use of molecular markers is Quantitative Trait Loci (QTL) mapping. QTL mapping is the use of markers which are known to be closely linked to alleles that have measurable effects on a quantitative trait. Selection in the breeding process is based upon the accumulation of markers linked to the positive effecting alleles and/or the elimination of the markers linked to the negative effecting alleles from the plant's genome. Molecular markers can also be used during the breeding process for the selection of qualitative traits. For example, markers closely linked to alleles or markers containing sequences within the actual alleles of interest can be used to select plants that contain the alleles of interest during a backcrossing breeding program. The markers can also be used to select toward the genome of the recurrent parent and against the markers of the donor parent. This procedure attempts to minimize the amount of genome from the donor parent that remains in the selected plants. It can also be used to reduce the number of crosses back to the recurrent parent needed in a backcrossing program. The use of molecular markers in the selection process is often called genetic marker enhanced selection or marker-assisted selection. Molecular markers may also be used to identify and exclude certain sources of germplasm as parental varieties or ancestors of a plant by providing a means of tracking genetic profiles through crosses.
Mutation breeding is another method of introducing new traits into pepper varieties. Mutations that occur spontaneously or are artificially induced can be useful sources of variability for a plant breeder. The goal of artificial mutagenesis is to increase the rate of mutation for a desired characteristic. Mutation rates can be increased by many different means including temperature, long-term seed storage, tissue culture conditions, radiation (such as X-rays, Gamma rays, neutrons, Beta radiation, or ultraviolet radiation), chemical mutagens (such as base analogs like 5-bromo-uracil), antibiotics, alkylating agents (such as sulfur mustards, nitrogen mustards, epoxides, ethyleneamines, sulfates, sulfonates, sulfones, or lactones), azide, hydroxylamine, nitrous acid or acridines. Once a desired trait is observed through mutagenesis the trait may then be incorporated into existing germplasm by traditional breeding techniques. Details of mutation breeding can be found in Principles of Cultivar Development by Fehr, Macmillan Publishing Company, 1993.
The production of double haploids can also be used for the development of homozygous lines in a breeding program. Double haploids are produced by the doubling of a set of chromosomes from a heterozygous plant to produce a completely homozygous individual. For example, see Wan et al., Theor. Appl. Genet., 77:889-892, 1989.
Descriptions of other breeding methods that are commonly used for different traits and crops can be found in one of several reference books (e.g., Principles of Plant Breeding, John Wiley and Son, pp. 115-161, 1960; Allard, 1960; Simmonds, 1979; Sneep et al., 1979; Fehr, 1987; “Carrots and Related Vegetable Umbelliferae”, Rubatzky, V. E., et al., 1999).
Proper testing should detect any major faults and establish the level of superiority or improvement over current cultivars. In addition to showing superior performance, there must be a demand for a new cultivar that is compatible with industry standards or which creates a new market. The introduction of a new cultivar will incur additional costs to the seed producer, the grower, processor and consumer for special advertising and marketing, altered seed and commercial production practices, and new product utilization. The testing preceding release of a new cultivar should take into consideration research and development costs as well as technical superiority of the final cultivar. For seed-propagated cultivars, it must be feasible to produce seed easily and economically.
Pepper is an important and valuable field crop. Thus, a continuing goal of plant breeders is to develop stable, high yielding pepper hybrids that are agronomically sound. The reasons for this goal are obviously to maximize the amount of fruit produced on the land used as well as to improve the fruit qualities. To accomplish this goal, the pepper breeder must select and develop pepper plants that have the traits that result in superior parental lines for producing hybrids.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification.